Now and for the foreseeable future, retinal prostheses for treating blindness are expected to possess extremely low bandwidth, i.e. pixel resolution, compared to the native capacities of a visual system including an intact retina. Thus, efforts have been made to improve the performance of retinal prostheses by operating on the pixel values produced by their imaging cameras using standard image processing techniques. Unfortunately, such efforts have not improved such prostheses to the extent necessary to enable them to become useful in providing substantial assistance to visually-impaired users desiring to engage in various everyday tasks (e.g., navigating stairs, recognizing faces, counting money). These efforts may have been hindered at least in part because the pixel intensities registered by such cameras tend to be dominated by idiosyncratic information that is largely irrelevant to the visually-impaired user in view of the task at hand.